1. Technical Field
The present invention relates in general to the recovery of oil from unconventional reservoirs and, in particular, to an improved system, method and apparatus for a thermal wellhead having a high power or voltage cable for in-situ upgrading and processing unconventional oil reservoirs.
2. Description of the Related Art
The increasing requirement for hydrocarbon processing and boosting in relation to efficient hydrocarbon field development has generated the need for highly reliable power and distribution systems. The growing power requirements to enable efficient and economic boosting of hydrocarbons have demanded significant development in power systems.
For example, the requirements for surface or subsea components are driven by the transmission distance and power needs for each application. Analysis must be undertaken to define and design a complete power distribution system. One type of subsea electrical connection forms a part of a high voltage (HV) termination system and can be used in pressure compensated systems, or as a high pressure barrier to penetrate a pressure vessel. Another example comprises an HV, wet-mateable connector for HV electrical power cables in subsea applications. This connector uses cable termination technology with an in-situ dielectric conditioning system for the connector internals. This design ensures a reliable make-up subsea over a range of performance, such as 12, 24 or 36 kV/500 A. These power connectors provide wet make-up of underwater electrical interfaces, typically between power cables and electrical power consuming equipment. Following mechanical interlocking and sealing of the connector halves, stroking of the connector takes place in a benign environment created by in-situ flushing and conditioning of the di-electricum.
These connectors are large, however, and are not suitable for all types of production applications, particularly those requiring wellheads with smaller diameters. For example, certain types of non-conventional hydrocarbon environments, such as shale beds, require numerous smaller wells to produce hydrocarbons in separate production wells. The shale is typically heated with electrical or microwave heaters using cables that are deployed in the smaller “heater wells” that extend through the shale beds. The oil is collected in the separate production wells that extend parallel to the heater wells. A thermal wellhead is located at the top of each of the heater wells, and is relatively small in diameter. The above-described solutions for HV applications are far too large to be effectively utilized in such operations. Thus, an improved system, method and apparatus for a thermal wellhead having HV requirements for in-situ upgrading and processing of unconventional oil reservoirs would be desirable.